| 摘要 |
PURPOSE:To easily carry out the extraction of an expander material from parison by previously forming an uneven wall thickness and extruding the parison, and then placing the thick wall parts into contact with molding surface parts by movable expander parts, and after expanding the thin wall parts, effecting blow-molding thereto. CONSTITUTION:A parison 5 is extruded such that the content of a reinforcing material in an inner peripheral part 22 is made higher than the content of a reinforcing material in an outer peripheral part 21. By this way, the contraction coefficient of the inner peripheral part 25 is made lower than the contraction coefficient of the outer peripheral part 21 in the cooling time of the parison 5, resulting in restraining the sticking of the parison 5 to an expander material 4 due to this contraction. Since the strength thereof is made higher, entangled parts never occur in the inner peripheral part 22 of the parison 5. Thus, the extraction of the expander material 4 from the parison 5 is rendered easy after the expansion of the parison 5. |
